Apparatus for introducing marking strips into sheet stacks

Abstract

Apparatus for the frontal introduction of marking strips (24), which are automatically formed, into a sheet stack (26) comprises a strip feeding device (18, 74-90) for supplying the marking strips (24) from a supply roll (20); a tongue (36) which is moved frontally into the sheet stack profile, lowered onto the stack (26), raised again and then retracted from the stack under the next deposited sheet (100); a guide channel (90) for the strip (22) supplied by the strip feeding device which opens into a gap under the lowered tongue (36); and a severing device (92) for severing the introduced marking strip (24) from the strip supply. The tongue (36) has downwardly bent flanks (40) that form a flat wedge, the guide channel (90) thereby opening into the channel (42) inside the tongue. The tongue is retracted in a loop-like movement while it is being slightly raised. It is then lifted upward before being moved in again while, for the most part, remaining outside the stack profile. The subject apparatus may be used on the front side (the side opposite the sheet supply side) of a stacker (6) having guide belts (28) running over it which leave little free space above the stack.

What is claimed is: 
     
       1. Apparatus for frontally introducing marking strips into a stack of sheets as the stack is being formed, said apparatus comprising, in combination: (a) strip feeding means for supplying the marking strips from a strip supply roll, said strip feeding means including a guide channel for receiving and guiding the strip supplied from said roll;   (b) a tongue for inserting said strips into said stack of sheets, said tongue having downwardly bent, wedge-shaped flanks forming a channel for the receipt of said strip from said guide channel;   (c) means, disposed between said guide channel and said tongue, for severing the strip supplied to said tongue from the strip in said guide channel; and   (d) means, coupled to said tongue, for moving said tongue frontally into the stack profile from a starting point above the stack of sheets, lowering said tongue onto said stack, retracting said tongue from said stack with a loop-like movement while said tongue is slightly lifted, and raising said tongue to said starting point again while said tongue remains substantially outside the stack profile.   
     
     
       2. The apparatus defined in claim 1, wherein said tongue moving means includes a "link motion" guide for guiding the motion of said tongue. 
     
     
       3. Apparatus defined in claim 2, wherein said link motion guide comprises, on the one hand, a loop type guide part and, on the other hand, a straight guide part. 
     
     
       4. Apparatus defined in claim 2, wherein said link motion guide comprises a switch tongue. 
     
     
       5. Apparatus defined in claim 1, wherein said tongue moving means includes a main drive cylinder. 
     
     
       6. Apparatus defined in claim 5, wherein said main drive cylinder is a single-action cylinder and said tongue moving means further includes a return spring. 
     
     
       7. Apparatus defined in claim 5, wherein the movement of said main drive cylinder is redirected from a substantially vertical movement, by way of an elongate flexible strip, to a substantally horizontal movement. 
     
     
       8. Apparatus defined in claim 1, wherein said severing means includes a knife blade and means for pivoting said knife blade about a transversely extending axis. 
     
     
       9. Apparatus defined in claim 8, wherein said pivoting means moves said knife blade in response to movement of said tongue.